A New Second-Derivative Spectrophotometric Method for the Determination of Vildagliptin in Pharmaceutical dosage form

An accurate derivative spectrophotometric method was developed and validated for the determination of dipeptidyl peptidase inhibitor vildagliptin in the pharmaceutical dosage form. The second derivative of the UV spectra has enabled the estimation of vildagliptin absorbance at 217 nm without any interferences. Linearity, precision, accuracy, detection (LOD), and quantification (LOQ) limits were established for method validation. Calibration curve was linear in the range of 10-60 µg/mL with a regression coefficient of 0.998. The method was validated as per the International Conference on Harmonization (ICH Q2 (R1)). The limit of detection and the limit of quantification were found to be 2.06 µg/mL and 6.25 µg/mL, respectively. Intra and interday precision data illustrated that the method has acceptable reproducibility as the percentage relative standard deviation (RSD) was less than 2 %, which indicates the precision of the method. The recovery was 98.39 % by the standard addition method. The percentage assay of vildagliptin was 98.06 % which showed good applicability. The following results indicate that the procedure is accurate, precise, and reproducible while being simple and less time-consuming. The method was demonstrated to be adequate for routine analysis in quality control.

Quantification of Platinum in Edible Mushrooms Using Voltammetric Techniques

Edible mushrooms are a food source with interesting nutritional values. The chief objective of this research was to develop a consistent method for the quantitative ultra-trace analysis of Pt in mushrooms, which is complex because it cannot be readily quantified by common analytical procedures. This research is one of the first analytical methods to establish Pt amount in these vegetables. In this research, 28 different edible mushroom samples from Italy were investigated. Determination of Pt in mushrooms was completed using Differential Pulse Voltammetry (DPV). In this study, we applied the standard addition method because there are no certified reference mushrooms containing platinum group elements on the market. The platinum quantification limit was 0.03 µg kg−1 d.w. In the analyzed samples, platinum amount was in the range of 0.03–73 µg kg−1. Our mushroom samples had a Pt content lower than the concentrations recommended by international establishments for other foodstuffs. In the future, the optimized method could be used for the analysis of plant and animal matrices intended for food supply.

Fast and Environment-Friendly GC-MS Method for Eleven Organophosphorus Flame Retardants in Indoor Air, Dust, and Skin Wipes

Organophosphorus based flame retardants (OPFRs) extensively used as alternatives to banned polybrominated diphenyl ethers and hexabromocyclododecane have been garnering interest due to the possibility that these compounds may have less significant impact on human and environmental health. Long pretreatment time, larger consumption of organic solvents, matrix interferents, and cross-contamination were found in previous studies while assessing OPFRs in indoor environments. We developed and optimized the extraction methods and simultaneous analysis of 11 OPFRs in indoor air, dust and skin wipe samples using the GC-MS approach. The proposed methods were validated using a standard addition approach, dust SRM 2585 and the real samples. Our procedures enabled the analyst to effectively limit coextracted interferences and simultaneous analytical methods of 11 target OPFRs for three matrices were achieved. The validation was performed according to standard guidelines (relative errors were identified by the analytes: −19% to 18% for indoor air, −11% to 14% for house dust, −15% to 16% for skin wipe). Good practices for quality assurance and quality control were well stated. The current high-Eco-scored methods could be categorized as “an excellent green analysis”. All analytes for the target OPFRs were detected in the real samples of indoor air, house dust and skin wipe collected from ten Taiwanese homes. Tris(2-butoxyethyl) phosphate, tris(1,3-dichloro-2-propyl)phosphate and tris(chloroisopropyl) phosphate were the most abundant OPFRs. Rapid, green and cost-effective GC-MS methods were developed and validated for the analysis of eleven OPFRs in indoor air, house dust and skin wipes.

THE DETERMINATION OF ETHYL P-METHOXY CINNAMATE IN KAEMPFERIA GALANGA L. RHIZOME EXTRACT HARVESTED IN RAINY AND DRY SEASONS

Objective: Kaempferia galanga L. rhizome (KGR), has been empirically used in Indonesia, particularly by Javanese, to cure inflammation. KGR contains various secondary metabolites which explain its pharmacology activities, among them is ethyl p-methoxycinnamate (EPMC). However, due to the different seasons of our country, the yield of extraction is often unalike. In this work, we determined the percentage of yield (w/w), the water content (thermogravimetric method), and the concentration of EPMC in the Ethanol extract of Kaempferia galanga L. Rhizome (EEKG) harvested from the rainy (EEKG-R) and dry seasons (EEKG-D). Methods: The sun-dried rhizomes were cold macerated for 3x24 h with 70% ethanol, filtered, and the solvent was evaporated at 40-45 °C until a viscous extract was obtained. The determination of EPMC in the extract was carried out using the RP-HPLC standard addition method. Detection was set at 308 nm; injection volume 20 µl; flow rate 1.0 ml/min. The column used is C18 (length 250 mm, internal diameter 4.6 mm, particle size 5 µm). Results: The yield of EEKG-R (harvested in the rainy season) = 14.56% w/w, water content = 4.37%, and the EPMC = 0.01%. Meanwhile the yield of EEKG-D (harvested in the dry season) = 5.79% w/w, water content = 18.76%, and the EPMC = 0.001%. Conclusion: Different climates affect the percentage yield and the quality of the extract. In our work, the EEKG-R (harvested in the rainy season) revealed a better quality compared to that of EEKG-D (harvested in the dry season) This study gives important information to standardize and optimize the harvest time of KG rhizomes for drugs development, which are strongly influenced by seasonal differences.

A Portable Sensor System with Ultramicro Electrode Chip for the Detection of Heavy-Metal Ions in Water

In this study, an ultramicro interdigital electrode array chip (UIEA) was designed and fabricated by using Micro-Electro-Mechanical systems (MEMS) technology, and a portable detection system, using the chip for determination of heavy-metal ions in water, was developed. The working electrode of the UIEA was modified with gold nanoparticles by electrodeposition. The detection sensitivity of the UIEA chip for copper ions was 0.0138 μA·L·μg−1, with the linear range of 0–400 μg/L and the detection limit of 18.89 μg/L (3σ), which was better than that of the compared columnar glassy carbon electrode. The results of the interference experiment verified that the UIEA chip has a certain anti-interference ability against common heavy-metal ions in water, such as Pb2+, Zn2+, and Mg2+ ions. The standard addition method was used to investigate the performance of the developed s ystem for copper ion determination in real water. The recovery range from 87.5% to 94.7% was achieved.

SIMPLE AND HIGHLY SELECTIVE DIRECT STABILITY INDICATING ULTRAVIOLET AND INDIRECT VISIBLE SPECTROPHOTOMETRIC METHODS FOR DETERMINATION OF ENROFLOXACIN IN PHARMACEUTICALS

Three simple, economic, selective and accurate and precise spectrophotometric methods are developed for determination of enrofloxacin (EFX) in pharmaceuticals. Method A is based on the measurement of absorbance of EFX in 0.1M HOAc at 315 nm. The ketoxime formation reaction has been employed in method B, in which the absorbance measurement of EFX oxime product at 275 nm is described. The third method (Method C) is indirect one and is based on the oxidation of EFX by cerium(IV), reaction of unreacted cerium(IV) with p-toludine (p-TD) and measurement of coloured solution at 540 nm. The Beer’s law is obeyed in the concentration ranges of 1.2–24, 1–8, and 1–20 μg/mL EFX in methods A, B, and C, respectively, with the corresponding molar extinction coefficients of 1.52×104, 3.86×104, and 6.6×103 L/mol/cm. The regression coefficients of calibration lines are 0.9996, 0.9913, and –0.9965, in methods A, B, and C, respectively. The limits of detection (LOD) and quantification (LOQ) have also been reported for each method. The methods have been validated to check accuracy, precision, robustness and ruggedness. The application of the methods proposed to determine EFX in tablets has been described and the results have been compared with a standard method. The results of validation and application have been found to be with excellent agreement. The standard addition procedure has been adopted in recovery experiments to further ascertain the accuracy of the methods and the results of the experiments are well satisfied. The stability indicating ability of Method A has been studied by subjecting EFX to acid and alkaline hydrolysis, oxidative, thermal and UV degradation followed by measurement of absorbance of resultant EFX solutions at 315 nm. The results of degradation study indicated unsusceptible nature of EFX to any of the stress conditions.

SPECTROPHOTOMETRIC METHODS FOR DETERMINATION OF SOFOSBUVIR AND DACLATASVIR IN PURE AND DOSAGE FORMS

Objective: Two simple, sensitive and accurate spectrophotometric methods have been developed for the determination of sofosbuvir (SOF) and daclatasvir (DAC) in pure forms and pharmaceutical formulations. Methods: The proposed methods are based on the oxidation of SOF and DAC by a known excess of cerium(IV) ammonium nitrate in sulphuric acid medium followed by determination of unreacted cerium(IV) by adding a fixed amount of indigo carmine (IC) and alizarin red S (ARS) dyes followed by measuring the absorbance at 610 and 360 nm, respectively. The experimental conditions affecting the reaction were studied and optimized. Results: The beer’s law was obeyed in the concentration ranges of 0.2-3.0, 0.2-4.0 for SOF and 0.5-4.5 and 0.5-5.0 μg/ml for DAC using IC and ARS methods, respectively with a correlation coefficient ≥ 0.9991. The calculated molar absorptivity values are 2.354 × 104, 1.933 × 104 for SOF and 1.786 × 104 and 2.015 × 104 L/mol. cm for DAC using IC and ARS methods, respectively u. The limits of detection and quantification are also reported. Intra-day and inter-day precision and accuracy of the methods have been evaluated. Conclusion: The methods were successfully applied to the assay of SOF and DAC in tablets and the results were statistically compared with those of the reference method by applying Student’s t-test and F-test. No interference was observed from the common tablet excipients. The accuracy and reliability of the methods were further ascertained by performing recovery studies using the standard addition method.

Rapid Screening of Butyl Paraben Additive in Toner Sample by Molecularly Imprinted Photonic Crystal

In consideration of the endocrine disrupting effects caused by the butyl paraben (BP), a portable visual sensor has been developed based on the photonic crystal and molecular imprinting technology for the rapid screen of BP in toner sample, which is a type of aqueous cosmetic to soften the face skin. By integrating the self-reporting and molecular recognition properties, the molecular imprinting photonic crystal (MIPC) sensor can display obvious color changes regularly according to the concentration of BP. Based on the “color guide”, the content of BP in toner sample can be estimated directly with the naked eye. In addition, the Bragg diffraction spectrum of MIPC can red shift linearly with the increase of the concentration of BP in sample solution with correlation coefficient as 0.9968. The quantitative determination of BP can be achieved through the optical fiber spectrometer with detection limit as 0.022 mmol·L−1. With good selectivity, this MIPC film can recognize BPs against the complex sample matrix, showing a standard addition recovery of 107% for the real samples.

Pipette Tip Solid-Phase Extraction Combined with Fluorescence Spectroscopy for Determination of Selenium in Green Tea Samples

In this study, the custom-built pipette-tip solid phase extraction (PT-SPE), was used for pre-concentrating the selenium (Se) in green tea samples. The PT-SPE was prepared using a pipette tip and C18 as the adsorbent that was placed between glass wool. This method afforded several advantages in terms of efficiency of extraction time (8 min), sample (2 mL), and solvent (1 mL) volumes with less wastage of solvent. Under optimal conditions of extraction, this method yielded good linearity (r2=0.998) for the Se calibration curve and good limit of detection (0.2 μg/L) and quantification (0.6 μg/L). The standard addition method was used to remove the matrix effect. The recovery percentages of tea samples spiked with different Se concentrations ranged from 97.7 to 106.0%, indicating that the proposed method would be suitable for the determination of Se in green tea samples.